In recent years, compactness, high output, and high quality have been required in rotary electric machines such as electric motors or generators. With regard to downsizing rotary electric machines of this kind, stator windings that have concentrated windings in which conductor wires are wound onto individual stator core teeth have been used with a view to downsizing coil ends that do not generate effective magnetic flux. However, stators that use stator windings of distributed winding construction that can suppress torque pulsation and increase output are in demand. In addition, demand for induction machines that do not use magnets has also increased due to steep rises in magnet prices, and there is demand for stators that use higher-efficiency distributed winding stator windings.
Here, in contrast to concentrated windings, which are configured by winding conductor wires onto individual teeth, windings that are configured by winding conductor wires into slots that are separated by greater than or equal to two slots are designated “distributed windings”. In other words, distributed windings are wound such that a conductor wire that extends outward from one slot spans two or more consecutive teeth and enters another slot.
In conventional rotary electric machines such as that described in Patent Literature 1, winding coils that are formed into a coil shape by winding a rectangular conductor wire a plurality of times, also known as “hexagonal coils”, are housed in respective pairs of slots that are separated by a predetermined number of slots to constitute a distributed winding stator winding.
In conventional rotary electric machines such as that described in Patent Literature 2, winding assemblies that are produced by simultaneously bending and folding conductor wire groups that are formed by arranging a predetermined number of conductor wires at a pitch of one slot are mounted into a rectangular parallelepiped core, and that core is subsequently rolled into an annular shape to constitute a distributed winding stator winding.
In addition, in conventional rotary electric machines such as that described in Patent Literature 3, a plurality of U-shaped conductor segments are inserted from a first axial end of a stator core into pairs of slots that are separated by a predetermined number of slots, and end portions of the conductor segments that extend outward from a second axial end of the stator core are joined together by welding to constitute a distributed winding stator winding.